Environmentally benign anti-icing or deicing fluids

ABSTRACT

Deicing compositions comprised of hydroxyl-containing organic compounds and/or organic acid salts are disclosed.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.09/675,495, filed Sep. 29, 2000, now allowed, which in turn is acontinuation-in-part of application Ser. No. 09/436,811, filed Nov. 9,1999, now allowed, which in turn is a continuation of application Ser.No. 09/161,865, filed Sep. 28, 1998, now U.S. Pat. No. 5,980,774, issuedNov. 9, 1999, which in turn is a continuation-in-part of applicationSer. No. 08/940,936, filed Sep. 30, 1997, now U.S. Pat. No. 5,876,621,issued Mar. 2, 1999.

FIELD OF THE INVENTION

The present invention relates to deicing fluid compositions and methodsfor deicing surfaces. More particularly the present invention relates todeicing fluid compositions comprising hydroxyl-containing organiccompounds and/or certain organic acid salts that are relativelyenvironmentally benign.

BACKGROUND OF THE INVENTION

Freezing point lowering compositions are in widespread use for a varietyof purposes, especially to reduce the freezing point of an aqueoussystem so that ice cannot be formed or to melt formed ice. Generally,freezing point lowering compositions depend for their effectiveness uponthe molar freezing point lowering effect, the number of ionic speciesthat are made available and the degree to which the compositions can bedispersed in the liquid phase in which the formation of ice is to beprecluded and/or ice is to be melted.

The most pervasive of the commonly used products for deicing are commonsalt, calcium chloride and urea, with common salt (sodium chloride)being the least expensive and most commonly used. Common salt is widelyused to melt ice on road surfaces and the like. In this manner the saltforms a solution with the available liquid in contact with the ice andthereby forms a solution with a lower freezing point than the ice itselfso that the ice is melted. Chloride salts however suffer from relativelysevere drawbacks, such as the harmful effects on surrounding vegetationby preventing water absorption in the root systems, the corrosiveeffects on animal skin such as the feet of animals, clothing, roadwaysand motor vehicles, and the deleterious effects on surface and groundwater. Thus, any new method of deicing or new deicing composition thatcan reduce the amount of chloride salts would solve a long felt need inthe art.

For example, in roadway deicing applications, liquid calcium chloride(32%) is typically the preferred material when temperatures are too lowfor rock salt to be effective. However, the use of chloride salts oftenis not permitted or needs to be reduced in certain areas because of itshighly corrosive nature, which causes destruction of surroundingvegetation, damage to roadways and vehicles, and contamination of watersupplies.

Another drawback of certain prior art deicing fluids is the highchemical and biological oxygen demand that make them environmentallyunfavorable. The glycols are exemplary of deicing fluids thatparticularly suffer from this type of environmental drawback. Thus, anynew method of deicing or new deicing composition that can reduce theamount of glycols would solve a long felt need in the art.

Due to the problems associated with deicing agents as described above,there have been attempts to prepare even more deicing agents. For,example, Kaes, U.S. Pat. No. 4,448,702, discloses the use of afreezing-point lowering composition and method that calls for theaddition of a water-soluble salt of at least one dicarboxylic acidhaving at least three carbon atoms, such as a sodium, potassium,ammonium or organoamine salt of adipic, glutaric, succinic or malonicacid.

Peel, U.S. Pat. No. 4,746,449, teaches the preparation of a deicingagent comprising 12-75% acetate salts, trace-36% carbonate salts, 1-24%formate salts and 1-32% pseudolactate salts that is prepared from a pulpmill black liquor by fractionating the black liquor into a low molecularweight fraction and concentrating the collected low molecular weightfraction to produce the deicing agent.

U.S. Pat. No. 4,960,531 teaches that small amounts of methyl glucosides,i.e., less than 10%, in combination with a low amount, i.e., about 2.5%,of potassium carbonate can be employed as a trigger to conventional saltdeicers. The '531 patent is an improvement patent on U.S. Reissue Pat.No. RE 32,477 that teaches the use of a salt mixture of sodium andpotassium chloride and an amide. Other inorganic salts are also known tobe useful as freezing point lowering agents such as magnesium chloride,potassium phosphates, sodium phosphates, ammonium phosphates, ammoniumnitrates, alkaline earth nitrates, magnesium nitrate, ammonium sulfate,and alkali sulfates.

Special mention is also made of Sapienza, U.S. Pat. No. 5,876,621 andSapienza, U.S. Pat. No. 5,980,774 that disclose especially usefuldeicing and anti-icing compositions.

Solutions of low freezing point deicing and anti-icing agents typicallyinclude brines, ethylene glycol and propylene glycol solutions. The useof brines in anti-icing compounds can reduce, although not eliminate,the impacts of chlorides. Brines are used to transfer heat attemperatures below the normal freezing point of water. Ethylene glycolsolutions are well known for use as coolants for automobiles and thelike in regions in which the temperature may fall below the normalfreezing point of water. Ethylene and propylene glycols are used inrelatively large quantities at major airports in northern climates inorder to keep air traffic flowing during inclement weather. The fluidsgenerally are applied to the wings, fuselage and tail of aircraft aswell as the runways to remove ice. However, these glycol compoundslikewise have environmental drawbacks and can be detrimental to sewagetreatment processes.

Other prior art deicing fluids, such as alcohols, have toxic effects andhigh volatility particularly in the low molecular weight range and maybe the cause of offensive smell and fire danger. Furthermore, mono- andpolyhydric alcohols oxidize in the presence of atmospheric oxygen toform acids, which can increase corrosion of materials.

Yet another reason why new deicing fluids are needed emerges from therecent changes to the freezing point requirements of the SAE AMS 1435Aspecification for airport runway deicing fluids. Newer AMS 1435Aspecifications require deicing fluids to have a freezing point of lessthan −14.5° C. for a 1:1 weight dilution. These specifications are suchthat many technologies, including existing glycol-based fluids currentlyused commercially, no longer meet the new requirements, including ASTM D1177.

As such there exists in the art a need for new and improved deicingand/or anti-icing agents. Preferably these are free or substantiallyfree of inorganic salts, are environmentally benign and are preparedfrom relatively inexpensive raw materials while still possessingdesirable freezing point depression properties. Likewise, there alsoexists a need in the art for new deicing and/or anti-icing agents thatcan be used in combination with prior art deicing agents, such asinorganic salts or glycols, to substantially reduce the amount ofinorganic salts or glycols, and thereby concomitantly reduce theenvironmental affects of the salts and/or glycols. Surprisingly, it hasbeen found that compositions disclosed herein meet these needs.

The total active composition of the new deicing and/or anti-icing agentscan vary from about 5 to about 100 weight percent. Improved soliddeicers can be prepared that can be applied in the same manner as solidchloride salts with the environmental advantages described earlier.

SUMMARY OF THE INVENTION

Accordingly, in one preferred embodiment the present invention providesa deicing and/or anti-icing composition comprising (a) glycerols and (b)water.

In another preferred embodiment the present invention also provides amethod for de-icing or anti-icing a surface comprising applying to thesurface an effective amount of a de-icing agent and/or anti-icing agentcomprising glycerols and water.

In a further preferred embodiment of the present invention there isprovided a deicing and/or anti-icing composition comprising (a)glycerol, (b) an organic acid salt selected from the group consisting ofa carboxylic acid salt, a hydroxycarboxylic acid salt, a dicarboxylicacid salt and mixtures of any of the foregoing and (c) water.

In still a further preferred embodiment of the present invention thereis provided a method for de-icing or anti-icing a surface comprisingapplying to the surface an effective amount of a de-icing agent and/oranti-icing agent comprising (a) glycerols, (b) an organic acid saltselected from the group consisting of a carboxylic acid salt, ahydroxycarboxylic acid salt, a dicarboxylic acid salt and mixtures ofany of the foregoing and (c) water.

In another further preferred embodiment of the present invention thereis provided a deicing and/or anti-icing composition comprising (a) ahydroxyl-containing organic compound selected from the group consistingof hydrocarbyl aldosides including di- and polysaccharides such assucrose, sorbitol and other hydrogenation products of sugars,monosaccharides, maltodextrins and sucrose, maltitol, glycols,monosaccharides, glycerol and mixtures of any of the foregoing, (b) acarbonate salt and (c) water.

In still another further preferred embodiment of the present inventionthere is provided a method for de-icing and/or anti-icing a surfacecomprising applying to the surface an effective amount of a de-icingagent and/or anti-icing agent comprising (a) a hydroxyl-containingorganic compound selected from the group consisting of hydrocarbylaldosides including di- and polysaccharides such as sucrose, sorbitoland other hydrogenation products of sugars, monosaccharides,maltodextrins and sucrose, maltitol, glycols, monosaccharides, glyceroland mixtures of any of the foregoing, (b) a carbonate salt and (c)water.

It is still further contemplated that useful deicing and/or anti-icingagents can be prepared from combinations of sorbitol and glycerol withwater and with other materials such as carbonates and acetates, etc.These are especially useful for aircraft and airport runway deicingand/or anti-icing applications.

The present inventors have still further found that excellent deicingcompositions can be obtained by upgrading recovered airport and/oraircraft runoffs or other sources of recycled or recovered glycols(i.e., radiator fluids and gas dehydration glycol fluid). For example,the recovered runoffs, which typically contain at least about 5%,preferably at least about 10% by weight of glycol, or more, can beupgraded by adding effective amounts of (a) a hydroxyl-containingorganic compound selected from the group consisting of hydrocarbylaldosides, sorbitol and other hydrogenation products of sugars,monosaccharides, maltodextrins and sucrose, maltitol, glycols,monosaccharides, glycerols and mixtures thereof and/or (b) an organicacid salt selected from the group consisting of a carbonic acid salt, acarboxylic acid salt, a hydroxycarboxylic acid salt, a dicarboxylic acidsalt and mixtures thereof These upgraded runoffs can then be useddirectly as de-icing and/or anti-icing agents for surfaces such asbridges, runways and highways. Additionally, these can be used for thedeicing or anti-icing of almost any surface, including, but not limitedto particulate surfaces, such as salt, mineral ores and/or coal piles.

Another benefit of the present invention is seen in that whencarbohydrates are added to salts, such as potassium acetate, theviscosity and wetting abilities of the deicing and/or anti-icingcompound are increased. This has a dual effect of providing a compoundthat will not readily run off the surface, and of also providing a morepersistent film that does not leave a dry powder after the surface laterdries.

Further, in embodiments where some inorganic salt can be tolerated, suchas on certain highway applications, the present invention furtherprovides for upgrading recovered airport runoffs by addition ofeffective amounts of inorganic salts, such as sodium chloride, magnesiumand/or calcium chloride and the like. Such compositions have improvedenvironmental effects by reducing the amount of inorganic salts employedto obtain the same or better deicing and/or anti-icing properties.

The present invention still further provides a method for reducing theamount of inorganic salt necessary to achieve effective deicing and/oranti-icing, comprising adding to the inorganic salt, an effective amountof a deicing agent selected from the group consisting of glucosides,furanosides, maltosides, maltotriosides, glucopyranosides, sorbitols andother hydrogenation products of sugars, monosaccharides, maltodextrinsand sucrose, glycerols and mixtures of any of the foregoing.

The compositions and methods of the present invention can be applied toa wide variety of surfaces, including both metallic and non-metallicsurfaces of aircraft, which prevents icing, removes frozen water fromthe surface and prevents its reformation. The invention provides for adeicing composition that can be used on airplanes, runways, bridges,streets and the like. Further, the compositions can be used in heattransfer applications and other applications in which it is preferableto maintain a liquid in the unfrozen state, e.g., as in a fireextinguisher, car radiators, heat transfer systems, gas dehydrationsystems, lavatory fluids, protection of plumbing lines, drilling fluids,etc. In these applications, the compositions of the present inventioncan be use to replace completely or partially, or in addition to any ofthe glycols normally employed, including, triethylene glycol.Additionally, the present invention provides for an anti-icingcomposition that can be applied to a surface, such as bridges, prior tothe onset of icing conditions in order to prevent icing from occurring.Still further, the compositions of the present invention can be used asa deicer and/or anti-icer for pre-harvest fruits, vegetable crops andother vegetation, such as golf course greens.

In still further embodiments, the compositions of the present inventionare useful to prevent freezing or de-freezing in a wide variety of otherapplications. An example is that the compositions of the presentinvention can be used in drilling fluids used to break-up (melt) frozengas hydrates.

In another embodiment of the present invention, there is provided amethod of producing deicing and/or anti-icing formulations usingrecovered airport storm water as a medium for producing organic saltssuch as potassium acetate and potassium lactate in order to provide aglycol/organic acid salt deicing formulation.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention provides novel compositions useful as deicingagents and/or anti-icing agents. The deicing agents of the presentinvention comprise certain hydroxyl-containing organic compounds,certain organic acid salts, alone or in admixture with each other.

It is also envisioned that the compositions of the present invention canbe used in either a liquid or a solid format. For instance, the compoundcan be prepared as a liquid and sprayed on or spread on surfaces.Alternatively, it can be prepared in a solid form and employed as apowder. Optionally, the solid may be further processed using methodswell known in the art, such as, for example, pelletizing, prilling,flaking, or macerating to provide the formulation in a final useablepowdered or granular form. Any of the binders known to those skilled inthe art optionally may be present and may either be inert or may becomprised of components that actively help lower the freezing point. Forexample, cinders, sawdust, sand, gravel, sugars, maltodextrins andmixtures thereof and the like can be used.

The amount of deicing or anti-icing agent of the present invention thatis present in the total composition of the present invention can varyfrom about 5 to about 100 weight percent. Preferably, the de-icing agentand/or anti-icing agent is present in an amount ranging from about 5 or10 to about 90 weight percent, more preferably is present in an amountranging from about 15 to about 80 weight percent, and most preferably ispresent in an amount ranging from about 30 to about 70 weight percent.In many preferred embodiments, the deicing agents and/or anti-icingagents are used in about the same proportion as water, i.e., in a weightratio of about 1:1 agent:water. In solid formulations, the deicingand/or anti-icing agents may comprise 100% of the final formulation.

The hydroxyl-containing organic compounds useful in certain embodimentsof the present invention are generally selected from the group ofhydrocarbyl aldosides, sorbitol and other hydrogenation products ofsugars, monosaccharides, maltodextrins and sucrose, maltitol, glycols,monosaccharides, glycerols and mixtures thereof.

The hydrocarbyl aldosides useful in the practice of the presentinvention are known to those of ordinary skill in the art, such as thedi- and polysaccharides. An example of a hydrocarbyl aldoside is theglucopyranoside sucrose (table sugar). Preferably, the hydrocarbylaldosides comprise alkyl aldosides. Alkyl aldosides can be prepared, forexample, as described in U.S. Pat. Nos. 4,223,129 and 4,329,449 that areincorporated herein by reference.

Typical of the alkyl aldosides useful in the practice of the presentinvention are alkyl furanosides, alkyl maltosides, alkyl maltotriosides,alkylglucopyranosides mixtures thereof and the like.

Other hydroxyl-containing organic compounds useful in the practice ofthe present invention are sorbitol and other hydrogenation products ofsugars, monosaccharides, maltodextrins and sucrose, such as maltitol,xylitol and mannitol, glycols such as ethylene glycol and propyleneglycol, glycerols and monosaccharides and mixtures of any of theforegoing. These materials are available commercially and are well knownto those of ordinary skill in the art.

The organic salt components useful in the practice of the presentinvention include the carboxylic acid salts, the hydroxycarboxylic acidsalts, dicarboxylic acid salts and mixtures thereof.

The carboxylic acid salts that are useful in the practice of the presentinvention are likewise available commercially and are known to thoseskilled in the art. Carboxylic acid salts preferred for use in thepractice of the present invention comprise the sodium or potassium saltsof formates, acetates, propionates, butyrates and mixtures thereof Alsopreferred are potassium acetate and/or potassium formate.

The hydroxycarboxylic acid salts that are useful in accordance with thepresent invention are available commercially and are known to thoseskilled in the art. Preferred hydroxycarboxylic acid salts comprise thesalts of lactic acid, such as sodium lactate and potassium lactate.However, any of the cesium, sodium, potassium, calcium and/or magnesiumsalts of hydroxycarboxylic acids may be employed such as sodiumgluconate.

The dicarboxylic acid salts that are useful in accordance with thepresent invention are available commercially and are known to thoseskilled in the art. Preferred dicarboxylic acid salts comprise sodiumand potassium salts of oxalates, malonates, succinates, glutarates,adipates, maleates, fumarates and mixtures of any of the foregoing.

Also useful as a deicing component in certain of the compositions of thepresent invention are the high solubility carbonic acid salts. Preferredcarbonate salts for use in the practice of the present invention arepotassium carbonate, potassium bicarbonate, sodium carbonate and cesiumcarbonate. Potassium carbonate is especially preferred. In manyapplications, the addition of carbonic acid salts, such as potassiumcarbonate, has been found to provide synergistically unexpectedreductions in freezing points. For example, a 50/50 mixture of potassiumacetate and water has a freezing point of −60° C., as seen in Table 1,Example 9. When this solution is mixed with the 50/50 sorbitol watermixture from Table 1, Example 1 (freezing point −11° C.) the resultingsoludion as reported in Example 23 has a freezing point of −32° C.,which is only 6° C. below the arithmetic average of the two base stocks.However, it was discovered that when combining potassium carbonatesolution from Example 7 (47% potassium carbonate in water, freezingpoint −20° C.) on a 1:1 basis with the 50/50 sorbitol/water mixture fromExample 1 (freezing point −11° C.), the resulting compound as reportedin Example 11 had the surprisingly low freezing point of −27° C., whichis 15.5° C. lower than the arithmetic average.

In certain instances, where the pH of the carbonic acid or its salt istoo high to meet regulatory or industry specifications, it iscontemplated herein to use a buffering agent to lower the pH toacceptable levels. Suitable buffering agents may be selected from any ofthe known buffering agents. Especially preferred is boric acid. Forexample, in highway applications, compositions including potassiumcarbonate and/or potassium bicarbonate in combination with ahydroxyl-containing component of the present invention or industrialprocess stream containing same, the pH in some formulation may be above12, and most state highway departments prefer deicers having a pH below12. An effective amount of boric acid or other buffering agent may beadded to reduce the pH of the deicing compounds to less than 12, i.e.,from about 11.5 to about 11.8 or lower, to meet the specifications.Alternatively, during the preparation of the carbonate, the pH can beadjusted by continued reaction to bicarbonate or separate addition ofsame.

Thus, the instant invention provides equally effective, but considerablyless expensive product than the prior art, as potassium carbonate of thepresent invention costs generally about 30% less than the commonly usedpotassium acetate of the prior art. Carbonic acid salts are availablecommercially and can be prepared by methods known to those of ordinaryskill in the art.

Generally the organic freezing point lowering agents useful in thepractice of the present invention may be used in solid form or mixedwith water as pure components. However, it is contemplated that thepresent invention may employ a number of industrial or agriculturalprocess streams that comprise a water soluble solution of carboxylicacid salts, hydroxycarboxylic acid salts and/or dicarboxylic acid salts.Although the purification of these materials is difficult due to theirsimilarity in solubility characteristics to water, the dilute industrialor agricultural streams may be used directly in the practice of thepresent invention. The present invention contemplates, for non-limitingexamples, the use of industrial or agricultural process streams selectedfrom the group consisting of a grain stillage (grain steepwaters), awood stillage, agricultural or milk fermentation processes, sugarextraction processes such a desugared sugar beet molasses and/ordesugared sugar cane molasses, hydrogenation products of sugars,monosaccharides, maltodextrins and sucrose and mixtures of any of theforegoing. Generally, the components of the present invention arepresent in or may be readily derived by alcoholysis of the industrialprocess streams.

Certain of these industrial process streams may include components suchas low molecular weight sugars, such as, for example, sorbitols,sucroses, maltoses and glucoses. Where desired, by subjecting thesewaste streams to alcoholysis (with an alkyl alcohol) under conditionssuch as reacting with an alkyl alcohol in the presence of a cationexchange material or other acid, or the addition of an alkyl alcohol toa heated fermentation liquor at least some of the sugars will beconverted to glucosides. For instance, ethanol treatment of a typicalagricultural fermentation process stream comprising glucose would be atleast partially converted to ethyl glucoside.

In addition to (a) the certain hydroxyl-containing organic compounds and(b) the certain organic acid salts, it is contemplated by the presentinvention that other organic components may be included in the deicingand/or anti-icing compositions of the present invention. Exemplary ofsuch materials are citrate salts such as sodium citrate; amino acids andtheir salts such as lysine glutamate, sodium pyrrolidone carboxylate andsodium glucoheptonate; lignin components such as lignin sulfonate; boricacid and its salts; sodium gluconate and other gluconic acid salts; andmixtures of any of the foregoing.

In the methods of the present invention, the deicing and/or anti-icingcompositions of the present invention are applied, such as by sprayingor injecting for liquid forms, or spreading for solid forms onto thesurface desired to be treated. In the case of deicing, the surfacealready has ice formed thereon or liquid is already in ice form, and thedeicing compositions of the present invention melt the ice alreadyformed and are further effective in preventing additional ice formation.In the case of anti-icing, upon learning of a weather forecast thatpredicts possible dangerous icing conditions, the roads, bridges,airplanes, runways, growing produce or other surfaces or liquids can bepretreated with the anti-icing compositions of the present invention insimilar manner in order to prevent ice formation on the treated surfacesor in the treated liquids.

In specific applications, certain embodiments of the present inventionare especially preferred due to certain regulatory or industryguidelines. For example, in the deicing and/or anti-icing of aircraft,it is preferred to use deicing and/or anti-icing agents of methylglucoside; a mixture of sorbitol and glycerol; or a mixture of methylglucoside, sorbitol and/or glycerol with sodium lactate and/or potassiumlactate.

For the deicing and/or anti-icing of runways, it is preferred to usedeicing and/or anti-icing agents of sodium lactate; potassium lactate; amixture of sodium lactate and potassium lactate; a hydroxyl-containingorganic compound in combination with sodium lactate, potassium lactateand/or potassium acetate; a mixture of sodium lactate and/or potassiumlactate with potassium acetate; or potassium carbonate.

For de-icing and/or anti-icing of pre-harvest fruits and vegetables,such as fruit trees or grape vines, it is preferred to use de-icingand/or anti-icing agents of a hydroxyl-containing organic compound incombination with an organic acid salt, particularly a lactate salt.

The present invention also provides for the re-use of glycols recoveredfrom airport collection systems for the de-icing and/or anti-icing ofbridges, runways and highways. Of course, glycols can be recovered orrecycled from other sources, such as, but not limited to, radiatorfluids and/or gas dehydration glycol fluids. Currently, pure glycols areused to de-ice and/or anti-ice aircraft. The practice of collecting theglycol solutions that run off aircraft, either by using dedicateddrainage systems or vacuum collection trucks, is increasing. However,the runway material cannot be collected efficiently and the salvagedmaterial is very dilute. The present inventors have found that the usedglycols can be recovered and reused as de-icing agents and/or anti-icingagents by upgrading these glycols and then re-applying the upgradedglycols. The upgrading of these glycols comprises the addition of apolyhydroxyl and/or organic acid salt to the recovered glycol. Also,where tolerable, the recovered glycols can be upgraded by the additionof inorganic salts, such as sodium chloride. The formulations of thepresent invention, such as sorbitol/glycerol or methyl glucoside can berecovered in the same way.

Generally, after application on the runway, the glycols are recovered inconcentrations of about 10-20 weight percent. In accordance with thepresent invention, the addition of from about 5 to about 50 weightpercent, preferably from about 30 to about 40 weight percent, based onthe total weight of the composition, of the hydroxyl-containing organiccompounds of the present invention, the organic acid salts of thepresent invention or combinations thereof provides for an effectiveupgraded glycol-recovered runoff, which can be reused for de-icingand/or anti-icing on bridges, for airport or aircraft deicing andhighways. Where inorganic salts can be tolerated, similar amounts ofinorganic salts alone, or in combination with the hydroxyl-containingorganic compounds and/or organic acid salts, may also be added.

In other situations where some inorganic salts can be tolerated, thepresent invention provides an improved method for reducing the amount ofsalt to be added to achieve an equivalent or better deicing and/oranti-icing effect, and thereby reduce the detriment to the environment.In these embodiments, the present invention provides for replacing aportion of the inorganic salt with the hydroxyl-containing organiccompounds of the present invention, the organic acid salts of thepresent invention, or a combination thereof.

The present invention also provides an advantageous method for producingdeicing and/or anti-icing formulations using recovered airport stormwater as a medium for production of organic salts, such as potassiumacetate and potassium lactate, in order to accomplish a glycol/organicacid salt deicing formulation. This advantageous method addresses twoissues: (1) the fact that the concentration of glycol or other deicingcomponent recovered in storm water is usually quite low—about 10% orless; and (2) transportation of contained water as a major cost item inliquid deicing formulations. Technologies to concentrate the storm waterare available, but the cost increases substantially as a function of thelevel of glycol concentration required.

Typically organic salts, such as potassium acetate, are produced byadding glacial acetic acid to a solution of potassium hydroxide. In themethod of the present invention, the KOH solution would be prepared ator near the airport by adding solid KOH to recovered storm watercontaining glycol instead of water. Glacial acetic acid would then beadded to produce the organic salt.

Since the airports are generally located at or near metropolitancenters, this method would produce the product near its point ofconsumption, reducing the cost of transportation. Further, by usingstorm water instead of water to produce the final formulation, a lowerconcentration of glycol is needed to achieve the desired finalconcentration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The testing results as reported in the examples below were obtainedusing the following procedures. Freezing points were determined by theASTM D 1177 method. A fluid sample was placed in a cold bath and cooledat a steady rate while monitoring the temperature of the sample andplotting temperature as a function of time. When ice crystals begin toform in a sample, the temperature remains constant until the entiresample freezes, creating an inflection point on the cooling curveindicative of the fluid freezing point. This test is useful indetermining the useable temperature range of a deicing fluid andprovides an indication as to the ice melting capability and dilutioncapacity of the fluid.

The Kinematic Viscosity of the fluid was determined by the ASTM D445method and is defined as a fluid's resistance to flow. Viscosity is animportant property of any fluid, and in the case of deicing fluids,viscosity is important in aspects of fluid application and adherence. Afluid with a very high viscosity may be too thick to spray throughapplication equipment, whereas a fluid with a very low viscosity may betoo thin to adhere to the treated surface and run off. An optimumviscosity permits a fluid to be applied easily with conventional sprayequipment and allows it to adhere to the. surface for extended periodsof time to prevent ice from forming on and bonding to the surface.

Conductivity is a measure of a fluid's ability or tendency to conduct anelectric current. This property is an important factor in determining ifa fluid is acceptable to be used near electrical wiring. Additionally,high conductivity can also lead to corrosion of metals, as corrosion isan electrochemical reaction.

The pH of a fluid may affect its compatibility with various materials ofconstruction it may contact (metals in particular). In order to minimizemetal corrosion, most deicing fluids are formulated to a pH that isneutral to slightly basic in order to keep the fluid within thepassivation range of the metals commonly used in construction.

COD and BOD were measured by standard EPA methods. COD is defined as theamount of oxygen required to chemically oxidize an organic compoundcompletely to carbon dioxide and water. It is expressed as grams O₂ pergram of compound. BOD is defined as the amount of oxygen consumedthrough the biodegradation of an organic compound by the action ofmicroorganisms. The BOD/COD ratio often provides useful information asto the biodegradability and rate of biodegradation of an organiccompound. Compounds that exhibit a high BOD or a high BOD/COD ratio,such as propylene glycol, can lead to rapid depletion of dissolvedoxygen in water, which can lead to fish kills in natural waterways. Thisis a potential hazard for deicing fluid run off into storm sewers andstreams. Ideally, a deicing fluid should biodegrade completely, but at amoderate rate that is less than that of propylene glycol.

The DOT corrosion test method used follows the NACE Standard TM-01-69(1976 revision) as modified by Pacific Northwest Snowfightersconsortium. This test is applicable to roadway deicing chemicals thatare likely to contact carbon steel structural materials used inapplication equipment, automobiles, bridges, etc. It is intended tosimulate accelerated conditions of repeated and prolonged exposures ofsteel substrates to dilute concentrations of deicing chemicals undercyclic wet-dry conditions. Deicing chemicals were evaluated for rate ofcorrosion of standard carbon steel substrate and compared with the ratesobtained for distilled water and 3% sodium chloride solutions ascontrols.

The following examples are provided for illustrative purposes and arenot to be construed to limit the scope of the claims in any mannerwhatsoever.

EXAMPLES 1-34

Deicing and/or anti-icing fluids were prepared from pure compounds inaccordance with the present invention. They were then tested forfreezing point, viscosity, conductivity, pH, COD, BOD and corrosion. MBSrefers to desugared beet molasses from Michigan Beet Sugar. The resultsare reported below in Table 1. EXAMPLE 1 2 3 4 5 6 7 8 9 10  CompositionSorbitol 50  0 0 0 0 0 0 0 0 0 MeG 0 50  0 0 0 0 0 0 0 0 Glycerol 0 050  0 0 0 0 0 0 0 Propylene Glycol 0 0 0 50  0 0 0 0 0 0 MBS 0 0 0 0 50 0 0 0 0 0 Sucrose 0 0 0 0 0 50  0 0 0 0 Potassium Carbonate 0 0 0 0 0 047  0 0 0 Sodium Formate 0 0 0 0 0 0 0 25  0 0 Potassium Acetate 0 0 0 00 0 0 0 50  0 Sodium Lactate 0 0 0 0 0 0 0 0 0 50  Water 50  50  50  50 50  50  53  75  50  50  Properties Freezing Point, ° C. −11  −16 −23−33  −16   −7.5 −20  −19.5  −60  −32  Viscosity, cSt 22° C.   7.6   8.4  4.5   6.0   4.9  10.4   4.3   1.9   3.8  16.9 −7° C.  39.4  40.4  15.8 26.3  15.0  44.7  11.5   4.5  10.2 110.3  Conductivity, mS/cm    0.003   0.668    0.003    0.002 294   <.001 880  354  654  401  pH   5.48  4.53   5.04   5.81   8.66   5.88 >13   7.91   9.87   7.19 COD kg/kg  0.60   0.63   0.68   0.82   0.32   0.53   0.04   0.04   0.34   0.47BOD kg/kg   0.34   0.34   0.33   0.53   0.13   0.24   <0.005   0.33  0.18   0.24 PNSDOT Corrosion  −3.1  −0.8  −3.5  −2.2  14.9   −2.58  0.3  68.2 −2.5 −1.8 EXAMPLE 11  12  13  14  15  16  17  18  19  20 Composition Sorbitol 25  0 0 0 0 0 25  0 0 0 MeG 0 25  0 0 0 0 0 25  0 0Glycerol 0 0 25  0 0 0 0 0 25  0 Propylene Glycol 0 0 0 25  0 0 0 0 025  MBS 0 0 0 0 25  0 0 0 0 0 Sucrose 0 0 0 0 0 25  0 0 0 0 PotassiumCarbonate 25  25  25  25  25  25  0 0 0 0 Sodium Formate 0 0 0 0 0 0 25 25  25  25  Potassium Acetate 0 0 0 0 0 0 0 0 50  0 Sodium Lactate 0 0 00 0 0 0 0 0 50  Water 50  50  50  50  50  50  53  75  50  50  PropertiesFreezing Point, ° C. −27  −33  −37  −52*  −36  −26  −22  −23  −34  −15 Viscosity, cSt 22° C.   8.4   9.5   7.2   6.7   6.5   10.3   9.2   9.2  6.4   6.9 −7° C.  27.5  32.4  19.8  22.1   16.1   33.9  32.9  71.9 23.5  27.3 Conductivity, mS/cm 466  486  470  476  532  444  424  377 414  391  pH   12.63  12.73   12.72   13.21   12.13   12.32   7.71  7.63   7.62   8.11 COD kg/kg   0.21   0.26   0.26   0.35   0.08   0.22  0.28   0.37   0.31   0.42 BOD kg/kg   0.16   0.10   0.18   0.19   0.08  0.14   0.20   0.15   0.16   0.24 PNSDOT Corrosion  −1.1  −0.5   −5.5  −6.4   −1.2   −6.6  13.8  77.4  28.0  43.5 EXAMPLE 21  22  23  24  25 26  27  28  29  30  Composition Sorbitol 0 0 25  0 0 0 0 0 25  0 MeG 0 00 25  0  0 0 0 0 25  Glycerol 0 0 0 0 25 0 0 0 0 0 Propylene Glycol 0 00 0 0 25  0 0 0 0 MBS 25  0 0 0 0 0 25  0 0 0 Sucrose 0 25  0 0 0 0 025  0 0 Potassium Carbonate 0 0 0 0 0 0 0 0 0 0 Sodium Formate 25  25  00 0 0 0 0 0 0 Potassium Acetate 0 0 25  25  25  25  25  25  0 0 SodiumLactate 0 0 0 0 0 0 0 0 25  25  Water 50  50  50  50  50  50  53  75 50  50  Properties Freezing Point, ° C. −21 −24 −32 −34 −41 −51.3 −40−31 −27 −29 Viscosity, cSt 22° C.   6.3   9.6   5.7   6.3   4.4   4.7  4.3   6.4  10.9  10.9 −7° C.  22.0  38.4  18.3  21.2  13.6  16.1  12.9 21.7  59.2  60.1 Conductivity, mS/cm 471  426  300  322  287  274  355 292  199  202  pH   8.21   7.76   8.87   8.90   8.88   9.33   8.83  8.87   7.61   7.60 COD kg/kg   0.18   0.31   0.43   0.47   0.44   0.59  0.33   0.42   0.49   0.53 BOD kg/kg   0.13   0.24   0.24   0.14   0.32  0.35   0.20   0.29   0.34   0.33 PNSDOT Corrosion  18.0  41.5  −2.5 −2.6  −2.5  −2.6  −2.6  −2.4  −1.3  −1.5 EXAMPLE 31  32  33  34 Composition Sorbitol 0 0 0 0 MeG 0 0 0 0 Glycerol 25  0 0 0 PropyleneGlycol 0 25  0 0 MBS 0 0 25  0 Sucrose 0 0 0 25  Potassium Carbonate 0 00 0 Sodium Formate 0 0 0 0 Potassium Acetate 0 0 0 0 Sodium Lactate 25 25  25  25  Water 50  50  50  50  Properties Freezing Point, ° C. −39  −44.3* −29  −27  Viscosity, cSt 22° C.   8.2   8.1   8.3  13.4 −7° C. 36.3  40.3  36.1  71.6 Conductivity, mS/cm 200  181  276  189  pH  7.51   7.90   8.32   7.55 COD kg/kg   0.54   0.61   0.37   0.48 BODkg/kg   0.36   0.40   0.25   0.25 PNSDOT Corrosion  −1.2  −0.7  −0.8 −0.3

EXAMPLES 35-38

Deicing and/or anti-icing compositions prepared in accordance with thepresent invention employing industrial or agricultural streams as atleast part of the deicing and/or anti-icing composition were tested forfreezing points. The results are set forth in Table 2. TABLE 2 Example35 36 37 38 Composition CSB 25 0 25 0 Potassium Carbonate 25 25 0 0 CMS0 25 0 25 Potassium acetate 0 0 25 25 Water 50 50 50 50 PropertiesFreezing Point, ° C. −44 −38 −48 −42CSB refers to Molasses Concentrated Separator Bottoms from Idaho BeetSugar (Amalgamated Sugar) having the following approximate composition:

% ON DRY % BY WEIGHT SUBSTANCE COMPONENT GROUPS Dissolved Solids (RDS)74.84 — Ash 22.81 30.47 Crude Protein 19.44 25.97 Nitrogen Compounds (AsN) 3.11 4.16 α-Amino Nitrogen Compounds 0.41 0.55 (As N) INDIVIDUALCOMPOUNDS Sucrose 13.13 17.54 Raffinose 3.96 5.29 Invert 0.020 0.027Betaine 8.95 11.82 Potassium 8.85 11.82 Sodium 1.98 2.65 Calcium 0.040.05 Chloride 1.83 2.44 Nitrate 0.70 0.94 Sulfate 2.1 2.8 PyrrolidoneCarboxylic Acid (PCA) 6.29 8.40 Tyrosine 0.28 0.38 Serine 0.05 0.07Isoleucine and/or Proline 0.47 0.63 Glutamic Acid 0.88 1.18 AsparticAcid 0.89 1.19 Threonine 0.015 0.02 Alanine 0.16 0.21 Valine 0.12 0.16Glycine 0.06 0.08

CMS refers to Concentrated Molassess Solids from Michigan Beet Sugar(Monitor Sugar) having the following approximate composition (DS=drysolids): Total Solids (Brix)   70% approx. Sucrose 26.5% on DS approx.Raffinose  5.0% on DS approx. Nitrogen Compound (as N)  3.5% on DSapprox. Crude Protein 22.0% on DS approx. Betaine  8.5% on DS approx.Amino Acids  0.5% on DS approx. Ash 30.0% on DS approx. Bulk Density11.2 lbs./gallon approx. Others  4.0% on DS approx.

EXAMPLE 39

A mixture of 25% by weight water, 65% by weight ethyl lactate and 10% byweight sodium lactate was prepared. No crystal formation was observed ata temperature of −50° C.

EXAMPLE 40

A mixture of 50% by weight water and 50% by weight ethyl lactate wasprepared. The mixture had a melting point of −18° C.

EXAMPLE 41

A mixture of 70% by weight water, 24% by weight ethyl lactate and 6% byweight sodium lactate was prepared. The mixture had a melting point of−25° C. as determined by DSC and a pH of 6.0. For comparison, a 70% byweight water/30% by weight ethylene glycol solution has a melting pointof −18° C.

EXAMPLE 42

The addition of 50% by weight of a 50% mixture of ethyl lactate in waterto a concentrated, filtered corn steep liquor (containing 50% water and50% solids comprising mostly lactic acid and sugars) caused a reductionin freezing point from −11° C. to −16° C. The addition of 2% by weightsodium lactate further reduced the freezing point to −20° C.

EXAMPLE 43

A mixture of 60% by weight water, 20% by weight sodium lactate, 2% byweight proline (an amino acid), 8% by weight sorbitol and 10% by weightsodium pyrrolidone carboxylate (sodium PCA) was prepared. No crystalformation at −35° C. was observed. The pH was 6.57. For comparison a 50%by weight solution propylene glycol has a freezing point of −36° C.

EXAMPLE 44

A mixture of 12% by weight methyl lactate, 44% by weight methylglucoside and 44% by weight water was prepared. A melting point of −18°C. was observed. The mixture had a pH of 5.

EXAMPLE 45

A mixture containing 35% by weight methyl lactate, 35% by weight methylglucoside and 30% by weight water has a melting point of −21° C. asdetermined by DSC.

EXAMPLE 46

A filtered concentrated liquid residue of a 50% mture of corn stillageand steepwater containing 50% by weight water with a freezing point of−12° C. is heated to 90° C. and treated with 5% ethanol for 8 hours. Theresulting mixture has a freezing point of −17° C. The addition of 2%sodium lactate further reduces the freezing point to −21° C.

EXAMPLES 47-53

Additional deicing and anti-icing fluids containing potassium carbonatewere prepared in accordance with the present invention. The results areset forth below in Table 3. TABLE 3 Example 47 48 49 50 51 52 53Composition Methyl Glucoside 10 10 0 0 0 15 0 Sodium Lactate 10 0 0 0 100 0 Potassium Lactate 0 10 0 0 0 15 0 Sorbitol 0 0 0 0 10 0 0 Glycerol 00 0 33 0 0 0 Propylene Glycol 0 0 30 0 0 0 25 Potassium Carbonate 40 4030 33 40 30 35 Water 40 40 40 34 40 40 40 Properties Freezing Point, °C. −16 −16 −16 −16 −14 −15 −18

EXAMPLES 54-61

Additional deicing and anti-icing fluids containing potassium carbonatewere prepared in accordance with the present invention and measured forBOD and COD values. The results are set forth below in Table 4. Forcomparative purposes, the COD and BOD for a 50/50 glycol/water mixturealso are provided. Also, for reference the COD and BOD, respectively,for the individual components are as follows: methyl glucoside (1.24,0.71), sodium lacate (0.86, 0.51), potassium lactate (0.75, 0.45),sorbitol (1.14, 0.70), propylene glycol (1.68, 1.14) potassium carbonate(0.00, 0.00), water (0.00, 0.00). TABLE 4 Example 54 55 56 57 58 59 6061 Composition Methyl 10 10 0 0 0 15 0 0 Glucoside Sodium Lactate 10 0 00 10 0 0 0 Potassium 0 10 0 0 0 15 0 0 Lactate Sorbitol 0 0 0 0 10 0 0 0Glycerol 0 0 0 33 0 0 0 0 Propylene 0 0 30 0 0 0 25 50 Glycol Potassium40 40 30 33 40 30 35 0 Carbonate Water 40 40 40 34 40 40 40 50Properties COD kg/kg 0.21 0.20 0.50 0.40 0.20 0.30 0.42 0.84 BOD kg/kg0.12 0.12 0.34 0.24 0.12 0.17 0.29 0.57

EXAMPLE 62

A useful formulation for non-chloride liquid deicing consists of asolution in water of approximately 34-weight percent potassium acetate,7.9 weight percent propylene glycol, 0.5 eight percent corrosioninhibitor and the balance water. This formulation has a freezing pointof −40° F. The following table shows two cases. In case 62A, the formulais prepared from potassium acetate purchased at the normal commercialstrength of 50 weight percent. In case 62B, potassium acetate isproduced at or near the airport site by dissolving dry KOH in stormwater and adding the requisite quantity of glacial acetic acid. Theglycol in both cases is provided from two sources—(1) a recoveredairport storm water containing 10 weight percent glycol, and (2)purchased commercial 90 weight percent glycol. Table 5 below shows theproportions of raw material required for each case. 62A 62B 50%potassium acetate 64.0 0.0 solid potassium hydroxide 0.0 18.3 glacialacetic acid 0.0 19.6 purchased 90% propylene glycol 5.5 2.2 recoveredstorm water - 10% propylene glycol 30.0 59.4 inhibitor 0.5 0.5 Total100.0 100.0

The advantages of operating in the manner of Example 62B are:

-   -   A principal objective of this operation is to dispose of as much        dilute storm water as possible. Case 62B consumes almost twice        as much storm water per unit of deicing fluid produced and sold.    -   Further to this same point, the storm water often has a negative        value since the airport often must pay to have the municipal        water treatment facilities handle this material.    -   The reduced quantity of purchased commercial glycol results in a        lower cost product.    -   Eliminating double shipment and the shipment of water in the 50%        commercial product reduces the potassium acetate cost.

From the above data it can be seen that excellent deicing and/oranti-icing materials can be obtained in accordance with the presentinvention.

Many variations of the present invention will suggest themselves tothose skilled in the art in light of the above-detailed description. Forexample, any industrial or agricultural process stream that containscarboxylic acid salts, hydroxycarboxylic acid salts and/or dicarboxylicacid salts may be used to prepare the compositions of the presentinvention. Additionally, a wide variety of glucosides, carbonates,hydrocarbyl aldosides, and a variety of combinations of the componentsof the present invention may be employed in the compositions of thepresent invention. All such obvious modifications are within thefull-intended scope of the appended claims.

The above-referenced patents, patent applications, test methods andpublications are hereby incorporated by reference.

1-45. (canceled)
 46. A method for reducing volatility of a deicing fluidcomprising mono and/or dihydroxy alcohols, said method comprisingreplacing at least a part of said mono and/or dihydroxy alcohols with aneffective volatility reducing amount of a hydroxyl-containing compoundhaving a boiling point higher than said mono and/or dihydroxy alcohol.47. The method as defined in claim 46 wherein said dihydroxy alcohol isselected from the group consisting of ethylene glycol, propylene glycol,and mixtures thereof.
 48. The method as defined in claim 46 wherein saidhydroxyl-containing compound is selected from the group consisting ofglycerol, sorbitol, hydrocarbyl aldosides, monosaccharides and mixturesthereof.
 49. The method of claim 46 wherein said deicing fluid comprisesan aircraft deicing fluid.